The present invention relates generally to valve assembles and more specifically to high speed valve assemblies for use in connection with air bag inflation apparatus.
In recent years efforts have been made to incorporate air bags into motor vehicles in order to reduce the possibility of injury to occupants of the vehicle in the event of an accident. Typically, these air bags incorporate an uninflated air bag or bladder, a source of pressurized gas and means for rapidly inflating the air bag or bladder from the source of pressurized gas in the event the vehicle is subjected to a high rate of deceleration such as occurs during an accident. While solenoid operated valves are extremely reliable, to date these types of valves have not been utilized in such air bag systems because they have been too slow acting to enable proper inflation of the air bag.
The present invention, however, provides a solenoid operated valve assembly which is capable of sufficiently fast operation so as to render it suitable for use in connection with such air bag systems. The solenoid valve of the present invention includes a primary valve member retained in a closed position by means of a fluid pressure and a secondary solenoid actuated valve member operative to control release of the holding fluid pressure acting on the primary valve member. Circuit means are also provided for controlling actuating current flow to the solenoid in response to a sensed impact upon the vehicle. Upon energization of the solenoid, the solenoid operates to initially open the secondary valve slightly thereby allowing fluid pressure to begin venting. This initial fluid flow results in an increased opening pressure being exerted on the secondary valve member thereby rapidly moving it to a further fully open position which immediately releases the closing fluid pressure acting on the primary valve member. The primary valve member will then be moved into a fully open position thereby allowing the pressurized gas contained within a reservoir to inflate the air bag so as to provide a cushion for the vehicle occupants.
Because the solenoid is only required to move the secondary valve member a relatively small distance, the size thereof may be kept small thus enhancing the speed of operation thereof. Further, because the secondary valve member is utilized to control release of the primary valve biasing pressure, it too can be of a relatively small size thereby facilitating rapid operation. By placing the secondary valve member in close proximity to the primary valve member, the volume of pressurized fluid required to be vented may be kept small thus allowing rapid venting of same without requiring a large vent passage.
The use of a combination solenoid and pressure actuated valve assembly of the present invention offers many significant advantages over presently existing systems. For example, design flexibility is greatly increased because the pressure reservoir and associated actuating valve assembly can be located in areas remote from the air bags themselves. This thus allows greater freedom in the placement of the air bags within the vehicle as well as increased freedom of placement for other vehicle components etc. which may be positioned in the same area as the stored air bags. Further, the present invention enables a single reservoir to be utilized to fill multiple air bags simultaneously if desired. Also, because the system of the present invention is reusable, it does not need to be replaced in the event of deployment during an accident but rather can be recharged. This may contribute significantly to reducing repair costs. Further, the system is well suited for periodic servicing and operational readiness inspection should these be desired.
Additional advantages and features of the present invention will become apparent from the subsequent description and the appended claims taken in conjunction with the accompanying drawings.